The present invention is directed to an improved torque transmission driver used to transmit torque from a torque generating source, such as a power drill, to a fastener for assembly of a structure or device, most notably where the fastener is small.
Torque transmission drivers have been commonly used in assembling structures and devices with threaded fasteners such as screws and bolts. Such torque transmission drivers transmit the torque created by a torque generator to the fastener to thread a fastener into an assembly. Various such torque transmission drivers have been provided in the past, usually having the shape of a drive end complementary to a recess in or projections from the heads of fasteners, with which they are used. Examples are drill chucks and screw drivers.
To illustrate, U.S. Pat. No. 2,397,216 issued in 1946 discloses a number of forms or shapes of torque transmission drive systems. Known are the hex-type and cruciform-type torque transmission driver such as the PHILLIPS® torque drive system. Also, U.S. Pat. No. 3,584,667 shows a torque transmission driver which has been widely used in automotive, aerospace and appliance manufacture and marketed under the brand name TORX®. Various lobe-type torque drive systems similar to the TORX® drive system are also shown in U.S. Pat. Nos. 5,025,688, 4,269,246, 4,006,660, 3,885,480, 2,969,250 and 2,083,092 issued between 1991 and 1938. See also U.S. Patent Application Pub. No. US 2010/0129176 published May 27, 2010.
Despite the previous developments in torque transmission drivers, there remains a need for a torque transmission driver with the capability to more rapidly locate and marry the driver to the recess of a fastener, to provide better torque transmission capability over past torque drivers, and to reduce strip out of the recess of the fastener and reduce variation in drive torque failures. This need has been particularly acute and long recognized in torque transmission drivers for small fasteners, where the recess in the head of the fastener is less than 0.100 inch, or less than 0.060 inch, in the major dimension. These small fasteners have been generally difficult to engage and maintain stabilized with the torque transmission driver during installation, have had reduced engagement with the torque transmission driver limiting the amount of torque that could be transmitted from the driver to the fastener, and have had fine threads that could more readily be cross threaded and/or stripped out during installation with previously known torque drivers. As a result, in the past special installation tools have had to be used for these fasteners, which in turn limited the serviceability and repair ability of the structure or device assembled using the fasteners. Moreover, because of variability in installation torque, the quality control of the assembly was difficult if not impossible to maintain with previous transmission torque drivers.
A torque transmission driver is presently disclosed that comprises a drive axis and a main body having a first end portion and a second end portion, where the first end portion is adapted to receive and transmit torque from a torque generating source to the driver, and where the second end portion opposite the first end portion has a key shape and a protruding lead end, the key shape is adapted to fit a recess in a fastener and has a major dimension of less than 0.06 inches and a minor dimension, and the protruding lead end has a taper between 10° and 30° from a plane perpendicular to the drive axis of the driver and different in shape than the key shape with at least a portion of the protruding lead end initiating at the major dimension of the key shape. Alternatively, the protruding lead end of the second end portion of the main body may have a taper between 15° and 25°, or between 18° and 22°.
Additionally, the protruding lead end of the second portion of the main body is shaped to match the recess in a fastener such that torque can be transmitted from the second portion of the main body to the fastener through the protruding lead end. The protruding lead end may have a shape selected from the group consisting of a cone shape, a dome shape, a trapezoidal shape, and a polyhedral shape. The protruding lead end may be magnetized such as to facilitate contact between the protruding lead end and a fastener.
The key shape in the second end portion of the main body may have a shape selected from the group consisting of a quadrasplinular, pentasplinular, hexasplinular, quadralobular, pentalobular, hexalobular, hexagonal, and pentagonal.
Also disclosed is a torque transmission driver adapted to drive a small fastener having a recess with a major dimension less than 0.1 inches that comprises a drive axis and a main body having a first end portion and a second end portion, where the first end portion is adapted to receive and transmit torque from a torque generating source to the driver, and where the second end portion opposite the first end portion has a key shape and a protruding lead end, the key shape is adapted to fit a recess in a fastener and has a major dimension of less than 0.10 inches and a minor dimension, and the protruding lead end has a taper between 10° and 30° from a plane perpendicular to the drive axis of the driver and different in shape than the key shape with at least a portion of the protruding lead end initiating at the major dimension of the key shape. Alternatively, the key shape of the second end portion of the main body may be adapted to fit a recess having a major dimension of up to 0.060 inch or of up to 0.040 inch in the fastener.